1. Field of the Invention
This invention relates to a camera having a multiple point distance measurement area system, and, in particular, to such a camera also having an orientation detection device that determines the orientation of the camera, e.g., whether the camera is in a horizontal or vertical position.
2. Description of Related Art
Conventional cameras having a focal point detection device can measure the distance between the intended subject and the camera if the camera is positioned such that the intended subject appears within the distance measurement area 101a (FIG. 3). The distance measurement area 101a is disposed in the center of a viewfinder 101. If the intended subject is not situated within the single distance measurement area 101a, however, the camera focuses on whatever appears within the distance measurement area 101a, i.e., something other than the intended subject. In order to avoid this problem, multiple distance measurement areas 100a-100c (FIG. 4) can be provided in the viewfinder 100. An intended subject appearing in one of the multiple distance measurement areas can be photographed by selecting that particular distance measurement area.
With such a multiple point distance measurement camera, the photographer chooses a mode by which a particular distance measurement area will be designated when a photograph is taken. The photographer can choose between three possible modes: an automatic mode, a manual mode, and a line-of-sight mode. If the photographer chooses to have the distance measurement area designated according to the automatic mode, the camera will designate a particular distance measurement area (100a, 100b, or 100c) automatically based upon a known method when a photograph is taken. For example, the camera can designate one of the areas (100a-100c) that contains an object that is closest to the camera as the area to be used for focusing. Alternatively, if the photographer chooses to have the distance measurement area designated according to the manual distance measurement area selection mode, the photographer must manually designate a particular one of the distance measurement areas (100a-100c) by actuating one or more controls on the camera prior to taking a photograph. According to another alternative, if the visual line input (line-of-sight) mode is chosen by the photographer, the camera will designate the particular distance measurement area that is most closely aligned with the photographer's line of sight according to a known method. For an example of a camera having the visual line input mode, see, for example, U.S. Pat. No. 5,225,862, the disclosure of which is incorporated herein by reference.
For the purposes of this disclosure, the orientation of the camera refers to whether the camera is being used in its landscape configuration or its portrait configuration. The landscape configuration, or horizontal position, refers to the situation in which the longer axis of the camera (i.e., the base) is positioned approximately parallel to the ground while a photograph is being taken. The portrait configuration, or vertical position, refers to the situation in which the base of the camera is approximately perpendicular to the ground when a photograph is being taken. A method of changing the control of a camera based upon its orientation is described in Japanese Laid-Open patent application No. 2-64513.
The conventional cameras, however, do not establish a particular one of the distance measurement area selection modes with respect to whether the camera is in the horizontal position or the vertical position. In other words, if the orientation of the prior art multiple point distance measurement camera is changed, the distance measurement area selection mode must also be verified or changed by the photographer. Consequently, failing to change the distance measurement area selection mode when the camera orientation is changed may result in missed opportunities or undesired photographs.